1. Field of the Invention
This invention relates to an armament system wherein a projectile, in cooperation with its launching tube, functions as a ram jet.
2. Prior Art
Various schemes have been proposed to provide a projectile with a velocity greater than that achieved by a conventional projectile launched by a pulse of combustion gas.
In U.S. Pat. No. 3,253,511, issued May 31, 1966, F. Zwicky shows a hollow, full bore, projectile, characterized as a ram jet, disposed in a launching tube filled with a mixture of gasses. The largest outer diameter of the projectile is equal to the inner diameter of the tube so that the projectile makes a travelling seal with the tube, and all flow of gas from forward to rear of the projectile occurs through the projectile. Gaseous propellant enters through a forward opening, ignites within the projectile, and exits through a rear nozzle. The projectile is provided with an initial acceleration by a first stage, solid propellant, rocket.
In U.S. Pat. No. 4,051,762, issued Oct. 4, 1977, E. Ashley shows a full bore projectile spaced forwardly of a sub-caliber cavity generator by a volume of liquid propellant. The cavity generator progressively injects liquid propellant into a combustion volume aft of the generator.
In U.S. Pat. No. 2,971,473, issued Feb. 14, 1961 to C. Raynaud; U.S. Pat. No. 3,411,403, issued Nov. 19, 1968 to C. A. Rodenberger; U.S. Pat. No. 3,418,878, issued Dec. 31, 1968 to S. A. Stricklin; and U.S. Pat. No. 3,880,044, issued Apr. 29, 1975 to Al Korr et al, there are shown projectiles which are progressively accelerated along an explosive lined launch tube by their shock wave causing detonation of the lining immediately behind it.
In U.S. Pat. No. 2,783,684, issued Mar. 5, 1957 to Y. A. Yoler; U.S. Pat. No. 2,790,354, issued Apr. 30, 1957 to Y. A. Yoler et al; U.S. Pat. No. 3,086,424, issued Apr. 23, 1963 to T. W. Liao and U.S. Pat. No. 3,613,499, issued Oct. 19, 1971 to F. T. Hubbard et al; there are shown means for accelerating a projectile through a gas filled launch tube wherein the expansion of the gas is initiated by means external to the tube.
In U.S. Pat. No. 3,008,669, issued Nov. 14, 1961 to Tanczos et al; U.S. Pat. No. 3,273,334, issued Sept. 20, 1966 to Tanczos et al; and U.S. Pat. No. 3,386,249, issued June 4, 1968 to G. L. Dugger et al; there are shown ram jet engines in which fuel is fed from within the engine to be combusted on a portion of the external surface of the engine.
In U.S. Pat. No. 3,726,219, issued Apr. 10, 1973, R. G. Bolick shows a cartridge case which remains with the projectile and serves as a ram jet engine external to the gun tube.
In "The Electrothermal Ramjet," J. Spacecraft, Vol 20, No. 6, Nov.-Dec. 1983, pp 603-610, P. J. Wilbur et al in FIG. 8 show an annular flow ram jet configuration wherein heat is provided to noncombustible propellant electrically, either electromagnetically or in the form of electrical current.